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Biomedical subjects

C Lassvik

Publications and source records attributed to C Lassvik.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effects of the platelet inhibitor ticlopidine on exercise tolerance in stable angina pectoris.

Coronary blood flow might be reduced by platelet aggregates or by vasospasm induced by platelet-produced thromboxane A2. Therefore the effects of the platelet inhibitor ticlopidine (500 mg daily) on platelet function and on exercise tolerance were investigated in a double-blind placebo-controlled study in 38 middle-aged men with stable incapacitating angina pectoris. Before and after 4 and 8 weeks of treatment, exercise tests were performed in warm and cold environments. The in vitro platelet reactivity to ADP was determined at rest and the plasma levels of beta-thromboglobulin (BTG) and platelet factor 4 (PF4) were measured before and immediately after exercise. There were no signs of increased platelet activity at rest or after exercise as judged by the levels of BTG and PF4. Despite a potent inhibition of platelet reactivity to ADP in vitro during ticlopidine treatment, the exercise tolerance was reduced in exercise tests in both warm and cold environments and in daily life. Therefore platelet activity does not seem to play any significant role in exercise tolerance in the stable phase of angina pectoris.

Adult↗
PubMed1986

Duplex scanning in presumably normal persons of different ages.

Ultrasonic duplex scanning was used for flow velocity measurement in the extracranial carotid vessels in 92 presumably healthy volunteers aged 20-82 and in 14 patients aged 23-72 with normal carotid vessels on angiography. Velocities were examined as a function of age, diameter, blood pressure, side, or position in the vessel. The peak systolic velocities and late diastolic velocities in the CCA showed an age-dependent decrease (p less than 0.001), and the same was true of the peak systolic velocity in the proximal ICA on the right side (p less than 0.05) and the late diastolic velocity in the right (p less than 0.01) and left (p less than 0.001) proximal ICA. The change in velocity was inversely correlated to diameter and blood pressure. The systolic and late diastolic velocities were significantly (p less than 0.05 and 0.001 respectively) faster in the left CCA at low position than in the right, and, conversely, in the right ICA (p less than 0.05) than in the left. At CCA high position faster diastolic velocities were noted than at CCA low, on both sides. All age-dependent quotients comprised a peak systolic velocity in the CCA, whereas the quotient between the late distolic velocities in ICA and high did not show age dependency. Reproducibility of peak systolic and late diastolic velocities in the CCA, ICA, and ECA, expressed as the mean percentage difference, varied between 6.4 +/- 4.6% and 12.7 +/- 6.4%.

Adult↗
PubMed1986

Intercrural differences of arterial blood-pressure and blood-flow in new-born infants.

Intercrural systolic blood-pressure differences did not exceed 10 mmHg in 22 healthy infants who were term, pre-term or small for their gestational age (three); as measured simultaneously in both legs with 3-cm wide thigh cuffs and mercury-in-silastic strain gauges around the calves. In 13 infants with indwelling umbilical artery catheter and normal angiographic findings in both legs, blood-pressure differences were similarly low in a majority of the infants, but in three of these intercrural differences of 15-20 mmHg were found. Resting and submaximal arterial leg blood-flow, measured with venous occlusion plethysmography, showed larger intercrural differences than blood-pressure, and did not add further information. The results indicate that simultaneous systolic blood-pressure measurements in the legs, with strain gauge plethysmography, is a simple and risk-free noninvasive method, suitable, for example, for diagnosing thromboembolism in infants. An indwelling umbilical artery catheter seems to interfere very little with the arterial circulation in the catheterized leg.

Birth Weight↗
PubMed1986

Ramp-function work test suitable for automatic computation.

Heart rate (HR) response to step-function and ramp-function (20 W/min) work tests was compared in 12 healthy subjects. For a given power output (P), HR was substantially lower in the ramp tests. The HR difference increased with power output and increasing difference in work time between the test types. The HR difference can be explained in terms of a drift component (which accounts for 1/3 of the difference) and a lag component (2/3). As a consequence of the HR differences, P for a given HR is higher in ramp tests. Work capacity expressed, for example as P170, can be determined in ramp tests, and the result can be translated to step-function P170. The precision in this translation is markedly improved if a steady-state period is incorporated into the ramp test.

Adolescent↗
PubMed1985

Prospective evaluation of the accuracy of duplex scanning with spectral analysis in carotid artery disease.

Prospective evaluation of duplex scanning of the carotid vessels was performed over a 2-year period in 125 consecutive patients (249 vessels) with transient ischaemic attacks or minor stroke. Defining disease as a stenosis of greater than 15% reduction of the vessel diameter, with subgroups of 16-49% stenosis, 50-99% stenosis and occlusion, the sensitivity obtained was 96%, specificity 93% and accuracy 94%. With the use of linear multiregression analyses further subgrouping into 50-75% and 76-99% stenosis was performed. The best predictive variables were, in decreasing order, peak systolic velocity, late diastolic velocity and the difference between peak systolic and late diastolic velocity in the internal carotid artery. The additional periorbital Doppler examination caused a slight improvement in determination coefficient and diagnostic accuracy.

Adult↗
PubMed1985

Duplex scanning and periorbital pulsed Doppler in the diagnosis of external carotid artery disease: analysis of causes of error.

The external carotid arteries (ECA) were examined by duplex scanning in 123 consecutive patients with transient ischaemic attacks (TIA) and minor stroke. Two occlusions and five out of six high grade stenosis were correctly classified, yielding a sensitivity of 88% defining disease as stenosis greater than 50. Specificity was 94% and accuracy was 93%. Nine low grade stenosis (less than 50%) and six normal vessels were judged as high grade stenosis. A possible cause of this overestimation was a compensatory flow increase in the ECA caused by an occlusion or high grade stenosis in the internal carotid arteries (ICA), either on the same side or bilaterally. This was supported by the finding of a significantly (P less than 0.05) higher retrograde flow velocity in the ipsilateral supratrochlear arteries (STA) in patients with high ECA flow velocity, as compared to those with normal ECA flow. Thus in the evaluation of a possible ECA stenosis, the condition of the ICA should be considered in order to avoid overestimation of ECA lesions. The additional examination of flow direction and velocity in STA gives an indication as to whether or not an ECA stenosis might be present.

Adult↗
PubMed1984

Tachycardias initiated by automatic antitachycardia pacemakers.

Available automatic tachycardia-terminating pacemakers cannot distinguish between physiological and pathological tachycardia and, consequently, electrical stimulation during sinus tachycardia can occur. In order to evaluate whether this might be an arrhythmogenic problem or not, the cardiac response in eight patients having paroxysmal supraventricular tachycardia treated with tachycardia-terminating pacemakers was studied during exercise. After tachycardia recognition, the implanted pulse generator automatically emits single or double critically timed premature stimuli for termination of the arrhythmia. Post-implantation examinations revealed successful tachycardia termination by the pacemaker at rest, without the addition of any antiarrhythmic drugs, in all eight patients. During exercise tests, the sinus rate in seven patients exceeded the programmed tachycardia trigger rate resulting in triggered pacemaker stimulation. The native supraventricular tachycardia was initiated in four cases. In one of these patients, two short episodes of probable ventricular tachycardia were also recorded. This study demonstrates the clinical value of post-implantation assessments with exercise tests concerning the problem of pacemaker-initiated tachyarrhythmias. Tachycardia-terminating devices can induce tachycardias, and individual precautions must be taken in order to prevent or minimize the risk of pacemaker reversion of sinus rhythm to paroxysmal tachycardia or hazardous arrhythmias.

Adult↗
PubMed1983

Electrophysiological effects of prenalterol on the cardiac conduction system.

The electrophysiological effects of prenalterol, a new beta-receptor agonist, in a dose of 100 micrograms/kg body weight given intravenously for 5 min, were studied in 13 patients with signs of sinus node dysfunction and/or conduction defects within or distal to the atrioventricular (AV) node. In nine patients with signs of sinus node dysfunction a significant reduction was found in corrected sinus node recovery time, on an average by 1955 +/- 640 ms (-61%, P less than 0.05) and in atrial refractoriness, by 61 +/- 21 ms (-20%, P less than 0.05). Similar but insignificant changes were also seen in the four patients with normal sinus node function. In eight patients with AV nodal dysfunction, a significant increase was found in the Wenckebach point, by 51 +/- 10 b.p.m. (+52%. P less than 0.01) and a decrease in the AH interval, by 23 +/- 9 ms (-14%, P less than 0.05). AV nodal refractoriness tended to decrease by 115 +/- 58 ms (-24%, NS). Similar changes were found in the five patients with normal AV conduction. Heart rate increased in all 13 patients, on an average by 28 +/- 5 b.p.m. (+44%, P less than 0.001) and systolic blood pressure by 18 +/- 8 mmHg (+13% P less than 0.01). In conclusion, prenalterol increased sinus node automaticity and atrial and AV nodal conductivity, but did not improve infranodal conduction. Thus, the drug might be useful in the treatment of patients with sinus node dysfunction as well as in patients with spontaneous or induced atrioventricular conduction abnormalities.

Adult↗
PubMed1983

Adjuvant intravenous sympathetic block with guanethidine in construction of arteriovenous fistulas for blood access.

A prospective randomized investigation of regional intravenous sympathetic block with guanethidine (RGB) was made in patients undergoing surgical construction of arteriovenous fistula (AVF) for vascular access. The blockade was preoperatively performed on chronically uraemic patients without previous vascular access surgery. The studied data were preoperative forearm blood flow, intraoperative fistula blood flow and flow resistance, and patency rates of AVF. Serial occlusion plethysmography showed a 152% increase in mean forearm blood flow in the RGB group, with significant (p less than 0.001) difference from the controls. The fistula blood flow resistance was decreased (p less than 0.05). The early failure rate was 1/17 among the patients treated with RGB and 3/17 in an otherwise comparable control group. RGB may be useful for reducing early failure rates after construction of AVF, by facilitating blood flow through the fistula.

Adolescent↗
PubMed1982

Diagnosis of carotid artery disease--comparison between directional Doppler, Duplex scanner and angiography.

Examinations with directional Doppler (DD) with 10 MHz transducer, and pulsed Doppler in combination with two-dimensional sector scanner with 3 MHz transducer (Duplex) were carried out on 100 vessels in 51 patients with transitory ischemic attacks (TIA) and minor stroke within the territory of the internal carotid artery before angiography. The question at issue was to evaluate the accuracy of both methods in discriminating between occlusion and stenosis. A correct diagnosis was made by DD in 92 vessels out of 100 and by Duplex in 98 out of 100. All nine occlusions were correctly diagnosed by Duplex, but only five of them by DD, while the four remaining vessels were considered as stenosis greater than 50%. Out of 15 stenoses greater than 50%, 14 were correctly detected by Duplex and 11 by DD. One patient with tortuous vessel without stenosis was classified as greater than 50% stenosis by Duplex, and one vessel with 1 mm lumen was called occlusion by Duplex and DD. In conclusion, the Duplex scanner offers increased possibility to differ between high-grade stenosis and occlusion of the carotid arteries as compared with earlier non-invasive techniques.

Adult↗
PubMed1982

Occurrence of lateral incompetent perforating veins of the calf. Usefulness of the posterior midline incision.

This investigation is an evaluation of the posterior approach for subfascial ligation of incompetent perforating veins (IPV) of the calf. The distribution of veins found incompetent at operation and the incidence of wound complications were studied. 39 patients with clinical multiple perforating vein insufficiency were operated on. At the end of the operation the crural fascia was sutured in half of them. The tissue pressure in the gastrocnemius muscle was measured in 13 patients postoperatively. 151 IPVs were found in the 39 legs operated on (3.8/ leg). 25% were found on the lateral side, and were inaccessible from a medial incision. Postoperative infection was noted in 3 patients and in a further 6 mostly minor skin necrosis with delayed healing occurred. The incidence of delayed healing was not influenced by fascia suture and the tissue pressure was normal in the 13 patients so examined. The posterior incision gives excellent access to both medial and lateral IPVs and makes possible resection of the short saphenous vein at the same time. This approach is useful when ulcers and stasis dermatitis are present on both medial and lateral sides or when there are medial IPVs and signs of incompetence of the short saphenous vein.

Adult↗
PubMed1982

Changes in human forearm blood flow after intravenous regional sympathetic blockade with guanethidine.

The effect of intravenous regional sympathetic blockade with guanethidine on total forearm blood flow and on muscle and skin blood flow in the forearm was studied in healthy humans, using venous occlusion plethysmography, 133Xe-clearance technique and skin temperature recordings. The total blood flow tripled in response to the blockade and the rise persisted for 2-3 days. The increase in blood flow was confined to the skin, with no demonstrable steal effect on muscle blood flow. The observations imply that this type of sympathetic blockade may be of therapeutic value in some vascular disorders of the hand, and as supportive treatment in vascular surgery on the extremities.

Adult↗
PubMed1981

Angina pectoris in the cold. Effects of cold environment and cold air inhalation at exercise test.

Patients with effort angina and a history of cold intolerance performed brief submaximal exercise bicycle test in various temperatures with separation of inspiration and room air. Exposure to a cold room (-10 degrees C) and inhalation of very cold air(- 35 degrees C) in a normal room caused a significant decrease in maximal workload. Heart rate, systolic blood pressure, and rate-pressure product were significantly higher during exercise when compared with findings in the normal room. The decrease in maximal workload correlated significantly to the increase in heart rate and rate pressure product during exercise in both conditions, and to the increase in systolic blood pressure at exposure to a cold room. Exposure to 10 and 0 degree C environmental temperature and inhalation of moderately cold air (- 10 degrees C) did not cause any significant changes in maximal workload, heart rate, blood pressure, or rate pressure product during exercise, compared to the findings in the normal room. In conclusion, skin cooling seems to be far more important in its effect on heart load and the working capacity in patients with effort angina than inhalation of moderately cold air; inhalation of very cold air, however, does cause changes in working capacity similar to those of exposure to a cold environment. Increase in heart work during exercise is likely to cause the decrease in working capacity observed both with skin cooling and cold air inhalation.

Angina Pectoris↗
PubMed1980

Umbilical artery catheterization in newborns. IV. Strain-gauge plethysmography for the diagnosis of catheter-related thrombo-embolism in the legs.

Strain-gauge plethysmography was performed shortly after withdrawal of the catheter in 48 of 49 newborn ifnats who had undergone umbilical artery catheterization. Plethysmorgraphy was used to find a noninvasive method for diagnosing catheter-related thrombo-embolism in neonates. The results were compared with the findings at aniography. The method permits simultaneous measurements of the systolic blood pressure and of the resting and submaximal blood flow in both legs. Nine infants howed angiographic signs of total or partial occlusion in one leg, and 8 of them were investigated with plethysmorgraphy. The systolic blood pressure was signifcantly reduced in ifants with total and/or partial occlusion, but the blood flow was reduced only in infants with total occlusion. The peak flow after sugrasystolic occlusion was significantly otener delayed in infants with thrombo-embolism in the leg.

Catheterization↗
PubMed1979

Effects of various environmental temperatures on effort angina.

Eleven patients with effort angina and a history of cold intolerance performed short-term bicycle exercise tests at various room temperatures, 20, 10, 0 and -10 degrees C, and a few patients also at -30 degrees C. A significant reduction of maximal working capability (expressed as maximal work load, MWL), limited by moderately severe angina, was found at -10 degrees C (7% +/- 1, SEM, P less than 0.05) compared with normal room temperature. At 0 and 10 degrees C changes of MWL were small and not significant, and at -30 degrees C no further decrease of MWL was seen. About half of the patients, however, showed a tendency toward a decrease in MWL with decreasing environmental temperature, and and the decrease in MWL correlated significantly with an increase in rate pressure product (RPP) during exercise at both 0 and -10 degrees C. Thus, the decrease in working capability on exposure to cold could be explained by an increase in heart work. Warming up effects of exercise, counteracting the cold-induced increase in peripheral vascular resistance, were indicated by a diminishing difference in systolic blood pressure between a cold and normal environment with increasing work time.

Angina Pectoris↗
PubMed1978

Reproducibility of work performance at serial exercises in patients with angina pectoris.

The reproducibility of serial upright exercises in patients with ischaemic heart disease was tested. Five short term exercises (4--8 min) with continuous load increase and with 30 min rest intervals between tests were used. No tendency to change was found concerning work time to appearance of angina (APT), maximal working time (MWT) or time for disappearance of angina after exercise (DPT). The coefficient of variation was low for APT and MWT but considerably higher for DPT, being 9, 5 and 27%, respectively. MWT was considered as the end-point of choice. The ST depression at MWT showed no tendency to change and the variation was moderate (14%), while at APT and DPT the variation was high (52%), but, likewise, with no tendency to change. The maximal heart rate increased slightly and significantly (P less than 0.001), while the maximal blood pressure was constant throughout tests, thus the maximal rate pressure product tended to increase. This indicates a slight improvement of the myocardial performance at serial exercises, which, however, does not affect the reproducibility of the anginal reaction.

Angina Pectoris↗